Biological fluid separation device

ABSTRACT

A biological fluid separation device adapted to receive a biological fluid sample having a first portion and a second portion is disclosed. The device includes a housing having a first chamber having a first chamber inlet for receiving the biological fluid sample therein and a first chamber outlet. The housing has a second chamber having a second chamber inlet and a second chamber outlet, and a separation member separating at least a portion of the first chamber outlet and the second chamber. The separation member is adapted to restrain the first portion of the biological fluid sample within the first chamber and to allow at least a portion of the second portion of the biological fluid sample to pass into the second chamber. An actuator, such as a vacuum source, draws the biological fluid sample into the first chamber and the second portion into the second chamber.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationSer. No. 62/302,296, entitled “Biological Fluid Separation Device”, andfiled Mar. 2, 2016, the entire disclosure of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Disclosure

The present disclosure relates generally to devices adapted for use withbiological fluids. More particularly, the present disclosure relates todevices adapted for separating components of biological fluids.

2. Description of the Related Art

Blood sampling is a common health care procedure involving thewithdrawal of at least a drop of blood from a patient. Blood samples arecommonly taken from hospitalized, homecare, and emergency room patientseither by finger stick, heel stick, or venipuncture. Blood samples mayalso be taken from patients by venous or arterial lines. Once collected,blood samples may be analyzed to obtain medically useful informationincluding chemical composition, hematology, or coagulation, for example.

Blood tests determine the physiological and biochemical states of thepatient, such as disease, mineral content, drug effectiveness, and organfunction. Blood tests may be performed in a clinical laboratory or atthe point-of-care near the patient. One example of point-of-care bloodtesting is the routine testing of a patient's blood glucose levels whichinvolves the extraction of blood via a finger stick and the mechanicalcollection of blood into a diagnostic cartridge. Thereafter, thediagnostic cartridge analyzes the blood sample and provides theclinician a reading of the patient's blood glucose level. Other devicesare available which analyze blood gas electrolyte levels, lithiumlevels, and ionized calcium levels. Some other point-of-care devicesidentify markers for acute coronary syndrome (ACS) and deep veinthrombosis/pulmonary embolism (DVT/PE).

Blood samples contain a whole blood portion and a plasma portion. Plasmaseparation from whole blood has been traditionally achieved bycentrifugation which typically takes 15 to 20 minutes and involves heavylabor or complex work flow. Recently there are other technologies thathave been used or tried to separate plasma such as sedimentation,fibrous or non-fibrous membrane filtration, lateral flow separation,microfluidics cross flow filtration, and other microfluidicshydrodynamic separation techniques. However, many of those technologieshave various challenges arranging from poor plasma purity, analyte biasor requiring specific coating to prevent analyte bias, high hemolysis,requiring dilution, long separation time, and/or difficulty inrecovering the plasma. For example, most membrane based separationtechnologies suffer from an analyte bias problem, and often requirespecific coating treatments for the target analytes.

SUMMARY OF THE INVENTION

The present disclosure provides a biological fluid separation device,such as a blood separation device, and a separation process that allowshigh quality plasma to be generated in less than 1 minute. The bloodseparation device allows a single pressure source such as a vacuumsource, for example a vacutainer tube, to power the plasma separationprocess. The device design is simple, low cost, and disposable. Theplasma separation process is fast, easy to operate, and produces highquality plasma samples from whole blood. It is scalable from sample sizeof micron liters to milliliters. The separation process does not requireany hardware or electric power. It is operated by pressures which can begenerated by using a syringe draw and/or a vacutainer tube. The qualityof the separated plasma is comparable to that of tube plasma generatedby centrifugation and suitable for various diagnostic needs.

In accordance with an embodiment of the present invention, a biologicalfluid separation device is adapted to receive a biological fluid samplehaving a first portion and a second portion. The biological fluidseparation device includes a housing having a first chamber having afirst chamber inlet for receiving the biological fluid therein and afirst chamber outlet. The housing includes a second chamber having asecond chamber inlet and a second chamber outlet, and a separationmember separating at least a portion of the first chamber outlet and thesecond chamber. The separation member is adapted to restrain the firstportion of the biological fluid sample within the first chamber and toallow at least a portion of the second portion of the biological fluidportion to pass into the second chamber. The biological fluid separationdevice also includes an actuator in communication with a portion of thehousing, such that actuation of the actuator draws the biological fluidsample into the first chamber.

In certain configurations, the biological fluid is whole blood, thefirst portion is a red blood cell portion, and the second portion is aplasma portion. During use, actuation of the actuator draws the secondportion of the biological fluid through the separation member. Theactuator may be a vacuum source, such as a single vacuum source. Thevacuum source may be an evacuated tube.

In certain configurations, the second chamber is a plasma collectioncontainer. In other configurations, a plasma collection container isprovided in communication with the second chamber. The actuator may be asingle actuator which imparts a pressure to a portion of the firstchamber to draw the biological fluid into the first chamber, and impartsa pressure to a portion of the second chamber to draw a portion of thesecond portion of the biological fluid into the second chamber.

The separation member may be a track-etched membrane, such as apolycarbonate track-etched membrane. The biological fluid separationdevice may also include a vent in communication with a portion of thesecond chamber. The vent may be transitionable between a closed positionin which the vent seals the second chamber, and an open position inwhich the second chamber is vented to atmosphere. The vent may beprovided in the closed position during separation of the second portionof the biological fluid sample from the first portion of the biologicalfluid sample, and in the open position during removal of the secondportion of the biological fluid sample from the second chamber.

In accordance with another embodiment of the present invention, abiological fluid separation device is adapted to receive a biologicalfluid sample having a first portion and a second portion. The biologicalfluid separation device includes a housing having a first chamber havinga first chamber inlet for receiving the biological fluid therein and afirst chamber outlet. The housing also includes a second chamber havinga second chamber inlet and a second chamber outlet, and a separationmember separating at least a portion of the first chamber outlet and thesecond chamber. The separation member is adapted to restrain the firstportion of the biological fluid sample within the first chamber and toallow at least a portion of the second portion of the biological fluidportion to pass into the second chamber. The biological fluid separationdevice also includes an actuator, a first line in communication with theactuator and the first chamber, and a second line in communication withthe actuator and the second chamber. Actuation of the actuator draws thebiological sample into the first chamber via the first line, and drawsthe second portion of the biological sample into the second chamber viathe second line.

A single actuator may provide a first pressure to a portion of the firstchamber via the first line and a second pressure to a portion of thesecond chamber via the second line. In certain configurations, thebiological fluid is whole blood, the first portion is a red blood cellportion, and the second portion is a plasma portion. The actuator may bea vacuum source, such as a single vacuum source. The vacuum source maybe an evacuated tube.

In certain configurations, the second chamber is a plasma collectioncontainer. In other configurations, the biological fluid separationdevice includes a plasma collection container in communication with thesecond chamber. The separation member may be a track-etched membrane,such as a polycarbonate track-etched membrane.

In certain configurations, the biological fluid separation device alsoincludes a vent in communication with a portion of the second chamber.The vent is transitionable between a closed position in which the ventseals the second chamber, and an open position in which the secondchamber is vented to atmosphere. The vent may be provided in the closedposition during separation of the second portion of the biological fluidsample from the first portion of the biological fluid sample, and in theopen position during removal of the second portion of the biologicalfluid sample from the second chamber. A porous material may also bedisposed within at least a portion of the second line.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of thisdisclosure, and the manner of attaining them, will become more apparentand the disclosure itself will be better understood by reference to thefollowing descriptions of embodiments of the disclosure taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional representation of a biologicalfluid separation device, such as a blood separation device, inaccordance with an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the separation member of theblood separation device of FIG. 1 taken along line 2-2 in accordancewith embodiments of the present invention, with the separation memberseparating a plasma portion of a blood sample from a whole blood portionof the blood sample.

FIG. 3 is a top view of the housing of the blood separation device ofFIG. 1 in accordance with an embodiment of the present invention.

FIG. 4 is a perspective view of the blood separation device of FIG. 1 inaccordance with an embodiment of the present invention.

FIG. 5 is a table listing the input blood volume and output plasmavolume of performance testing of the device of FIG. 1 in accordance withan embodiment of the present invention.

FIG. 6 is a table listing the input blood volume and quality of theplasma sample void of first component portions achieved throughperformance testing of the device of FIG. 1 in accordance with anembodiment of the present invention.

FIG. 7 is a table listing the input blood volume and output plasmavolume of performance testing of the device of FIG. 1 in accordance withan embodiment of the present invention.

FIG. 8 is a graph illustrating the resulting output plasma and wasteblood portions as a function of Heparin concentration as a result ofperformance testing of the device of FIG. 1 in accordance with anembodiment of the present invention.

FIG. 9 is a flow chart illustrating exemplary modeling in accordancewith an embodiment of the present invention.

FIG. 10 is a schematic representation illustrating a track-etch membranefor a blood separation device in accordance with an embodiment of thepresent invention.

FIG. 11 is a flow chart illustrating exemplary modeling in accordancewith an embodiment of the present invention.

FIG. 12 is a flow chart illustrating exemplary modeling in accordancewith an embodiment of the present invention.

FIG. 13 is a flow chart illustrating exemplary modeling in accordancewith an embodiment of the present invention.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the disclosure, and suchexemplifications are not to be construed as limiting the scope of thedisclosure in any manner.

DETAILED DESCRIPTION

The following description is provided to enable those skilled in the artto make and use the described embodiments contemplated for carrying outthe invention. Various modifications, equivalents, variations, andalternatives, however, will remain readily apparent to those skilled inthe art. Any and all such modifications, variations, equivalents, andalternatives are intended to fall within the spirit and scope of thepresent invention.

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal”, and derivatives thereof shall relate to the invention asit is oriented in the drawing figures. However, it is to be understoodthat the invention may assume alternative variations and step sequences,except where expressly specified to the contrary. It is also to beunderstood that the specific devices and processes illustrated in theattached drawings, and described in the following specification, aresimply exemplary embodiments of the invention. Hence, specificdimensions and other physical characteristics related to the embodimentsdisclosed herein are not to be considered as limiting.

FIG. 1 illustrates an exemplary embodiment of a biological fluidseparation device, such as a blood separation device of the presentdisclosure. Referring to FIGS. 1 and 2, a blood separation device 10 ofthe present disclosure is adapted to receive a blood sample 12 having ared blood cell portion 14 and a plasma portion 16. The presentdisclosure provides a blood separation device and a separation processthat allows high quality plasma to be generated in less than 1 minuteand a blood separation device that allows a single pressure source suchas a vacuum source or a vacutainer tube to power the whole plasmaseparation process. The device design is simple, low cost, anddisposable. The plasma separation process is fast, easy to operate, andproduces high quality plasma samples from whole blood. It is scalablefrom sample size of micron liters to milliliters. The separation processdoes not require any hardware or electric power. It is operated bypressures which can be generated by using a syringe draw and/or avacutainer tube. The quality of the separated plasma is comparable tothat of tube plasma generated by centrifugation and suitable for variousdiagnostic needs. After collection of a blood sample, the bloodseparation device isolates the plasma portion of the blood sample, aswill be described herein, and may allow for transfer of the plasmaportion of the blood sample to a point-of-care testing device.

Referring to FIGS. 1 and 2, a blood separation device 10 generallyincludes a housing 20, a first chamber or blood chamber 22, a firstchamber inlet 24, a first chamber outlet 26, a second chamber or plasmachamber 28, a second chamber outlet 30, a separation member or membrane32, an actuator 34, a plasma collection container 36, and a vent 38.

In one embodiment, the housing 20 defines a first chamber 22 and asecond chamber 28. The first chamber 22 is adapted to receive a bloodsample 12. The first chamber 22 includes a first chamber inlet 24through which a whole blood sample is introduced and a first chamberoutlet 26 through which a separated first portion of the blood sampleexits the housing 20. The second chamber 28 includes a second chamberinlet which is directly adjacent the separation member 32 and a secondchamber outlet 30. A separation member 32 is disposed between the firstchamber 22 and the second chamber 28.

In one embodiment, the blood chamber 22 has a blood chamber length whichis significantly longer than a height or width of the blood chamber 22to improve the plasma separation efficiency. This may also increase aflow resistance of the blood, and thus require a higher pressure todrive the blood flow through the chamber. In one embodiment, a widerblood chamber can reduce flow resistance and the pressure needed todrive the blood flow. In some embodiments, the blood chamber geometry isbalanced and/or configured for the targeted plasma yield andcorresponding power source to operate the device.

The separation member 32 is adapted to restrain a first portion 14 orred blood cell portion of the blood sample 12 within the first chamber22 and allow a second portion 16 or plasma portion to pass through theseparation member 32 and into the second chamber 28, as shown in FIG. 2.Biological fluid, or blood, entering the first chamber 22 passes alongthe separation member 32 and the second portion 16 passes through theseparation member 32 through the second chamber inlet and into thesecond chamber 28 while the first portion 14 is restrained with thefirst chamber 22. In one embodiment, the second chamber 28 may be aplasma collection container. In another embodiment, a plasma separationcontainer 136, as shown in FIG. 4, may be provided in communication withthe second chamber outlet 30.

The separation member 32 comprises a plurality of pores dimensioned torestrain the first portion 14 of the blood sample 12 and to allow thesecond portion 16 of the blood sample 12 to pass therethrough. In oneconfiguration, the separation member 32 comprises a plurality of pores53, as shown in FIG. 2, dimensioned to prevent red blood cells, whiteblood cells, platelets and fragments thereof (the first portion 14),from passing through the separation member 32, while allowing the plasmaportion (the second portion 16) of the blood sample to pass through theseparation member 32. Optionally, the separation member 32 may be atrack-etched membrane. In one embodiment, the track-etched membranecomprises a polycarbonate membrane with a pore size of 0.4 μm and a poredensity of 1.5×10⁸/cm². In one embodiment, a separation member 32includes a pore size from 0.2 to 1 μm. In one embodiment, a separationmember 32 is formed of a material that can be PC, PET, PP, and/orcombinations thereof. In one embodiment, the separation member 32 issubstantially hydrophobic. In one embodiment, the pore density of aseparation member 32 can be from 5×10⁸/cm² to 1×10⁶/cm². In oneembodiment, the thickness of a separation member 32 can be from 8 to 100μm. In one embodiment, the water flow rate of a separation member 32 canbe in the range of 2.5 to 300 mL/min/cm² through the separation member32.

In other embodiments, the separation member 32 may include hollow fibermembrane filters or flat membrane filters. Membrane filter pore size andporosity can be chosen to optimize separation of clean (i.e., red bloodcell free, white blood cell free, and platelet free) plasma 16 in anefficient manner. In other embodiments, the separation member 32 maycomprise any filter that is able to trap the whole blood portion 14 inthe first chamber 22 and allow the plasma portion 16 to pass through theseparation member 32 and into the second chamber 28.

In one embodiment, the blood separation device 10 includes an actuator34. The actuator 34 is in communication with a portion of the firstchamber 22 and a portion of the second chamber 28. In one embodiment,actuation of the single actuator 34 imparts a pressure to a portion ofthe first chamber 22 to draw the biological fluid, such as the bloodsample 12, into the first chamber 22. Actuation of the actuator 34 alsoimparts a pressure to a portion of the second chamber to draw at least aportion of the second portion 16 of the biological fluid into the secondchamber 28. Accordingly, the actuation of the actuator 34 effectivelydraws the second portion 16 of the blood sample 12 through theseparation member 32 as the blood sample 12 passes along the firstchamber 22. The separation member 32 restrains the whole blood portion14 in the first chamber 22 and allows the plasma portion 16 to passthrough the separation member 32 and into the second chamber 28.

In one embodiment, the actuator 34 is a single actuator which provides afirst pressure P1 to a portion of the first chamber 22 and a secondpressure P2 to a portion of the second chamber 28, as shown in FIG. 1.In certain configurations, a vent 38 is provided in communication with aportion of the second chamber 28. The vent is transitionable between aclosed position in which the vent seals the second chamber 28 and allowspressure P2 to be provided by the actuator 34 to the second chamber 28,and an open position in which the second chamber 28 is vented toatmosphere. The vent 38 may be provided in the closed position duringseparation of the second portion 16 of the biological fluid sample 12from the first portion 14 of the biological fluid sample 12, and in theopen position during removal of the second portion 16 of the biologicalfluid sample 12 from the second chamber 28, such as by disconnecting theplasma collection container 136, shown in FIG. 4.

Referring again to FIG. 1, the blood separation device 10 includes ablood chamber 22, a plasma chamber 28, and a separation member 32 thatis operated by a pressure source, e.g., an actuator 34, to drive bothblood flow and plasma flow. The actuator 34 may be a vacuum source. Insome embodiments, the vacuum source can be from syringes, vacutainers,or other vacuum generators such as a Fluigent instrument. In otherembodiments, a practical vacuum source can be achieved by using asyringe pulled manually or with a syringe pump to create the vacuum. Thepower source can also be a vacutainer, or other evacuated tube. Inalternative embodiments, the plasma separation can be achieved bypushing blood from the blood inlet side, e.g., the first chamber inlet24, to flow over the separation member 32. In this case the pressuresource is a positive pressure which can be generated by syringes orcompressed air or other gaseous medium.

In one embodiment, the blood flow and plasma separation using a bloodseparation device 10 of the present disclosure is powered by pressure atthe inlet, e.g., the first chamber inlet 24, and the outlet, e.g., thefirst chamber outlet 26 and/or the second chamber outlet 30. In oneembodiment, the pressure at the blood inlet, e.g., the first chamberinlet 24, may be set to zero and the pressure at the first chamberoutlet 26 may be set at −5 psi. In one embodiment, the pressure at theplasma outlet, e.g., the second chamber outlet 30, may be set at −2 psi.In one embodiment, the pressure source is a vacuum source.

In one embodiment, the vent 38 is blocked during the plasma separationprocess and is optionally opened at the end of the plasma separationprocess to recover all of the plasma 16 from the plasma chamber 28. Thepressure setting can be adjusted to specific flow (or shear) rate. Inorder to achieve short separation time, a higher flow rate and shearrate are desired. In one embodiment, a blood flow rate of 3 to 5 mL/mincan be achieved using a blood separation device 10 of the presentdisclosure.

In one embodiment, the pressure source is the pressure to drive theblood flow and to create the trans-membrane pressure as the blood flowsthrough the chamber. In one embodiment, the trans-membrane pressureshould be large enough to drive the plasma flow through the separationmember 32 but small enough to keep blood cells from being trapped at thepore entrance or dragged through the membrane pore. In one embodiment,the “net transmembrane pressure” should be less than 5 psi, preferablyless than 2.5 psi.

In one embodiment, the pressure to drive the blood flow should bematched to the chamber geometry and targeted flow rate. The flow rate(more relevant to the fluid dynamics is the wall shear rate) should beuniform and large enough to prevent red blood cell deposit on to amembrane surface (cake layer formation). The shear rate should be belowa threshold to prevent shear induced hemolysis. This shear inducedhemolysis is also dependent on residence time under the shear. Thecombination effect from shear and time should be controlled.

A blood separation device 10 of the present disclosure provides abalanced blood chamber with a large chamber length, a small chamberheight, and a large chamber width that has a great separationefficiency. The pressure settings allow for a high flow rate and shearrate within a design target of separation time and input blood volume.Pressure settings also allow proper transmembrane pressure during theseparation process. The shear rate prevents blood cake formation asblood flows through the chamber over the membrane surface.

Referring again to FIG. 1, use of a blood separation device 10 of thepresent disclosure will now be described. In one embodiment, asdescribed above, the blood separation device 10 includes a blood chamber22 and a plasma chamber 28 which are separated by a separation member ormembrane 32, e.g., a track etched membrane. In one embodiment, themembrane 32 is part of the blood chamber 22 and at the same time part ofthe plasma chamber 28. The blood chamber 22 has a blood inlet, e.g., afirst chamber inlet 24, and an outlet, e.g., a first chamber outlet 26.The plasma chamber 28 has one or multiple outlets, e.g., a secondchamber outlet 30. Blood flows in through the inlet 24 of the bloodchamber 22 and tangentially over the membrane 32 surface, and exits fromthe outlet 26 of the blood chamber 22. Plasma 16 flows through themembrane 32 and enters the plasma chamber 28 which can be collected orstored in a secondary plasma container, e.g., a plasma collectioncontainer 36, for further diagnostic tests. For example, in oneembodiment, after separation, the blood separation device 10 is able totransfer the plasma portion of the blood sample to a point-of-caretesting device.

In one embodiment, the blood chamber 22 can be designed to allowtangential flow of the blood over the membrane 32 surface which can havedifferent shapes such as but not limited to rectangular, spiral, orserpentine etc. The size of the chamber can be varied to meet theapplication needs for the plasma volume. The inlet 24 and outlet 26 ofthe blood chamber 22 may be at a non-filtration area to maximize thetangential flow. In one embodiment, the plasma chamber 28 may match theblood chamber 22 to allow efficient utilization of the membrane 32. Inone embodiment, referring to FIG. 3, a design example may include arectangular chamber.

In one exemplary embodiment, the blood chamber 22 was a width W of 10mm, and a length L of 50 mm with the inlet 24 and the outlet 26 at eachend of the blood chamber 22. In one embodiment, the blood chamber 22 hasa height H that is 0.08 μm. In one embodiment, the plasma chamber has alength L of 10 mm, a width W of 4 mm, and a height H of 0.2 μm. In oneembodiment, ridges are created inside the plasma chamber 28 to supportthe membrane 32. The membrane 32 can be optionally secured onto theridges to prevent sagging. Alternatively the ridges can be built in theblood chamber 22 or on both chambers. In one embodiment, thetrack-etched membrane is a polycarbonate membrane with a pore size of0.4 μm and pore density of 1.5×10⁸/cm².

FIG. 4 illustrates another exemplary embodiment of a blood separationdevice of the present disclosure. Referring to FIGS. 4 and 2, a bloodseparation device 100 of the present disclosure is adapted to receive ablood sample 12 having a whole blood portion 14 and a plasma portion 16.The present disclosure provides a blood separation device and aseparation process that allows high quality plasma to be generated inless than 1 minute and a blood separation device that allows a singlepressure source such as a vacutainer tube to power the whole plasmaseparation process. The device design is simple, low cost, anddisposable. The plasma separation process is fast, easy to operate, andproduces high quality plasma samples from whole blood. It is scalablefrom sample size of micron liters to milliliters. The separation processdoes not require any hardware or electric power. It is operated bypressures which can be generated by using a syringe draw and/or avacutainer tube. The quality of the separated plasma is comparable tothat of tube plasma generated by centrifugation and suitable for variousdiagnostic needs.

In one embodiment, after collecting a blood sample, the blood separationdevice 100 is able to separate a plasma portion of the blood sample fromthe whole blood portion as described in more detail below. In oneembodiment, after separation, the blood separation device 100 is able totransfer the plasma portion of the blood sample to a point-of-caretesting device.

Referring to FIG. 4, a blood separation device 100 generally includes ahousing 120, a first chamber or blood chamber 122, a first chamber inlet124, a first chamber outlet 126, a second chamber or plasma chamber 128,a second chamber outlet 130, a separation member or membrane 132, anactuator 134, a plasma collection container 136, a first line or bloodline 150, a second line or plasma line 152, and a merged line 154. Inone embodiment, the first line 150 and the second line 152 are mergedinto line 154.

In one embodiment, the housing 120 defines a first chamber 122 and asecond chamber 128. The first chamber 122 is adapted to receive a bloodsample 12. The first chamber 122 includes a first chamber inlet 124 anda first chamber outlet 126. The second chamber 128 includes a secondchamber outlet 130. In one embodiment, the blood separation device 100includes a separation member 132 that is disposed between the firstchamber 122 and the second chamber 128.

The separation member 132 is adapted to trap the whole blood portion 14in the first chamber 122 and allow the plasma portion 16 to pass throughthe separation member 132 and into the second chamber 128, as shown inFIG. 2.

In one embodiment, the separation member 132 comprises a track-etchedmembrane. In one embodiment, the track-etched membrane comprises apolycarbonate membrane with a pore size of 0.4 μm and a pore density of1.5×10⁸/cm². In one embodiment, a separation member 132 includes a poresize from 0.2 to 1 μm. In one embodiment, a separation member 132 isformed of a material that can be PC, PET, PP, or other materials. In oneembodiment, a separation member 132 is hydrophobic. In one embodiment,the pore density of a separation member 132 can be from 5×10⁸/cm² to1×10⁶/cm². In one embodiment, the thickness of a separation member 132can be from 8 to 100 μm. In one embodiment, the water flow rate of aseparation member 132 can be in the range of 2.5 to 300 mL/min/cm²through the separation member 132.

In other embodiments, the separation member 132 may be either hollowfiber membrane filters or flat membrane filters. Membrane filter poresize and porosity can be chosen to optimize separation of clean (i.e.,red blood cell free, white blood cell free, and platelet free) plasma 16in an efficient manner. In other embodiments, the separation member 132may comprise any filter that is able to trap the whole blood portion 14in the first chamber 122 and allow the plasma portion 16 to pass throughthe separation member 132 and into the second chamber 128.

In one embodiment, a first line 150 is in communication with theactuator 134 and the first chamber outlet 126. In one embodiment, asecond line 152 is in communication with the actuator 134 and the secondchamber outlet 130.

In one embodiment, the blood separation device 100 includes a plasmacollection container 136 that is in communication with the secondchamber outlet 130. The plasma collection container 136 is able tocollect and store the separated plasma 16.

In one embodiment, the blood separation device 100 includes a porousmaterial within the second line 152.

In one embodiment, the blood separation device 100 includes an actuator134. The actuator 134 is in communication with a portion of the firstchamber 122 via the first line 150 and a portion of the second chamber128 via the second line 152. In one embodiment, actuation of theactuator 134 draws a blood sample 12 into the first chamber 122 and theseparation member 132 is adapted to allow the plasma portion 16 of theblood sample 12 to pass through the separation member 132 to the secondchamber 128. In one embodiment, the separation member 132 is adapted totrap the whole blood portion 14 in the first chamber 122 and allow theplasma portion 16 to pass through the separation member 132 and into thesecond chamber 128.

In one embodiment, the blood separation device 100 includes a bloodchamber 122, a plasma chamber 128, and a separation member 132 that isoperated by a pressure source, e.g., an actuator 134, to drive the bloodflow and plasma flow. In one embodiment, the actuator 134 is a vacuumsource.

In one embodiment, a single actuator provides a first pressure to aportion of the first chamber 122 via the first line 150 and a secondpressure to a portion of the second chamber 128 via the second line 152.

The blood separation device 100 with lines 150, 152 provides a systemthat requires only one pressure source to drive both blood and plasmasides of the device. The blood separation device 100 merges two lines150, 152 into one merged line 154. In one embodiment, a porous materialis added to the plasma vacuum line 152 to create air flow resistance.When a vacuum source is connected to the merged vacuum line 154, amajority of the power source is directed to the blood chamber 122through line 150 and powers the blood flow. A small portion of thevacuum is directed to the plasma chamber 128 through line 152 to drivethe plasma flow and trans-membrane pressure. The resister may be aporous polymeric disc with 1 micron meter pore size, such as thosecommercially available from Porax. It is noted, however, that the porousmaterial can be in many forms such as fiber, sintered polymericmaterials, porous metals, or any other air permeable materials.Alternatively, it can also be a small tube or channel built on a devicethat resists air flow. The merger for the two vacuum lines and porousmaterial can also be built or incorporated on the device directly.

An alternative design of the blood separation device 100 may incorporatea blood reservoir similar to the plasma reservoir for collecting bloodwaste, instead of using a vacutainer tube as the reservoir for the wasteblood. This may be beneficial when a centralized vacuum source is used.

Advantageously, the blood separation device 100 of the presentdisclosure allows a single pressure source to power the whole plasmaseparation process.

In one embodiment, the device design parameters (balanced blood chamberheight, width, and length) match the process parameter settings(Pressures P1 and P2 for driving blood flow and for providingtrans-membrane pressure, respectively). The matched system providestargeted flow rate and shear rate so that the cake formation isprevented on a membrane surface. The trans-membrane pressure drivesplasma flow through the membrane. If the design and process parametersare not matched, the plasma yield will be low and/or hemolysis willoccur. This matching is dominated by the design parameters if a certainflow rate and the uniformity of trans-membrane pressure along the lengthof the membrane are to be achieved. The trans-membrane pressureuniformity is affected by the pressure drop along the chamber length inthe blood chamber.

In one embodiment, the flow resister design and its incorporation in thedevice allow one single pressure source to drive blood flow and form thetrans-membrane pressure. The resister allows a small portion of thecommon vacuum source to be directed to the plasma side and providesufficient pressure to drive the plasma flow. The flow resister is builtin such a manner that it allows the restriction of airflow in the plasmaside but does not get into the plasma path. This simplifies the powersource requirement and plasma separation process. For example, theplasma separation can be achieved by connecting the device to a bloodsource and pushing a vacutainer to the device. Plasma is separated inless than one minute. This result is considered exceptional whencompared with prior designs which provide slow methodology and a lowyield of plasma, such as a production value of 50 μL or less plasma in10 minutes.

A blood separation device of the present disclosure provides asignificantly improved performance. The device and method of the presentdisclosure produces about 400 μL plasma in less than 1 minute using onethird of the membrane size of prior designs. In one embodiment, theblood separation device of the present disclosure uses a blood chambersize of 10 mm×50 mm×0.08 mm and a plasma chamber size of 10 mm×40 mm×0.2mm with an effective separation membrane area of 10 mm×40 mm. The bloodflow rate is 3 mL/min and the pressure settings are 5 psi vacuum forblood side and 2 psi vacuum for the plasma side. The input blood is at38% hematocrit. The process generated about 400 μL high quality plasmain one minute with very low hemolysis as indicated by low hemoglobinlevel in the plasma samples, as shown in FIG. 5. FIG. 5 illustratesplasma separation performance using a blood separation device of thepresent disclosure with normal heparinized whole blood at 38%hematocrit.

Plasma samples separated by using the method and blood separation deviceof the present disclosure are also analyzed using Sysmex to determinethe residue cells. The purity of the plasma is comparable to the controlsample obtained by conventional centrifugation process, as shown in FIG.6. Blood samples from different donors were tested and all performedconsistently on a blood separation device of the present disclosure.FIG. 6 illustrates plasma purity determined by Sysmex for samplesseparated using a blood separation device of the present disclosure withnormal heparinized whole blood at 46% hematocrit. The method and bloodseparation device of the present disclosure also performs very well withwhole blood at higher hematocrit (55%). The yield is about 250 μL withthe input volume of 3 mL as shown in FIG. 6.

FIG. 7 illustrates plasma separation performance using a bloodseparation device of the present disclosure with heparinized whole bloodat 55% hematocrit. The plasma samples also have very low hemolysis forhigh hematocrit input blood sample.

Plasma separation was also conducted successfully using the method andblood separation device of the present disclosure with normal freshblood with no anticoagulant added prior to plasma separation. Thisallows the device of the present disclosure to work with blood samplesdirectly from line draw without the need to add anticoagulant to theblood sample. When the device is loaded with heparin in the chambers attarget dosage, it can stabilize the blood and plasma during theseparation process. The heparin concentration can be designed to matchthe tube blood specification of 5 to 28 IU/mL. The plasma samplesproduced are stable and suitable for further diagnostic purpose. Thedata from FIG. 8 is obtained using a heparin activity test.

FIG. 8 illustrates plasma separation conducted successfully using themethod and blood separation device of the present disclosure with normalfresh blood (no anticoagulant added prior to plasma separation) at 42.6%hematocrit. The anticoagulant (heparin) is applied on device chambersand mixed into blood and plasma during plasma separation process. It isalso noted herein that a biological fluid separation device 10 of thepresent disclosure could be used for other sample management purposessuch as cell isolation, purification, and sample concentration.

It is noted herein that plasma generated using this invention containsdiagnostically relevant analytes. Examples of analytes that can betested directly from plasma separated using this technology include, butare not limited to those in general chemistry panels (e.g. potassium,sodium, calcium, magnesium, chloride, phosphate), triglycerides,cholesterol, high density lipoprotein (HDL)-cholesterol, low densitylipoprotein (LDL)-cholesterol, C-reactive protein (CRP), aspartatetransaminase/glutamic-oxaloacetic transaminase (AST/GOT), lipase,albumin, bilirubin, glucose, creatinine, IgG, ferritine, insulin,rheumatoid factors and prostate-specific antigen (PSA); hormones such asthyroid-stimulating hormone (TSH), free T3 Total T3, Free T4, Total T4,follicle-stimulating hormone (FSH) and beta human chorionic gondatropin(hCG); vitamins such as Vitamin D and Vitomin B12; and cardiac markerssuch as Troponin (cTnI, cTnT), b-type-natriuretic-peptide (BNP),NTproBNP, D-dimer, creatine kinase (CK), CK-MB, myoglobin. Additionalanalytes that can be tested from plasma separated using this technologyinclude, but are not limited to nucleic acids (e.g. circulatingcell-free DNA, microRNAs), exosomes, DNA viruses (e.g. Hepatitis-B) andRNA viruses (e.g. HIV).

Referring to FIGS. 9-13, another aspect of the present disclosure is asuite of fast-running, in-silica, analytical models that couples thephysics of cross-flow filtration, fluid dynamics transport, andhemolysis from filtration and shear forces. Such models calculate: (A) arepresentative viscosity of human blood under high shear rate conditionsas a function of hematocrit; (B) a representative pressure drop, flowrate, wall shear stress, wall shear rate, and representative fluidresidence time in rectangular channel above the filtration surface; (C)the volume of plasma generated by cross flow filtration through afiltration membrane with a representative pore radius and the plasmavolumetric flow rate through the filtration surface; and (D) a riskassessment of hemolysis caused by shear and filtration forces.

In one embodiment, the models of the present disclosure may be codedinto the scientific computer language MATLAB and are from a trained userwho specifies the model inputs and executes the analysis. Calculationsare performed in less than one minute and the user has rapid feedback onthe feasibility of a design's geometry and/or operating conditions basedon the potential volume of generated plasma, required fluid dynamics(flow, pressure, and shear), and hemolysis risk.

The models of the present disclosure are advantageous in that they arecapable of providing the same breadth of information in a much shortertime. For example, existing models that provide the same breadth ofinformation take weeks or even months to complete a single calculationor assessment of a single geometry. Moreover, the prior art modelsrequire many more additional parameters that each require their owndetailed investigation to determine appropriate values. Conversely,existing fast-running models target an individual physics area and donot couple or consider other physics at work (e.g., the filtrationperformance on the local fluid dynamics environment or hemolysisdependency on both the local fluid dynamics and filtration conditions).

Another improvement of the models of the present disclosure isimplementing all calculations in MATLAB using function-based andcalculation script(s) arrangements. The coding style leveragesplug-and-play capability from object-oriented programming techniques forfuture uses. Additionally, the MATLAB code was structured to enablerapid explorations of large design spaces through probabilistic oroptimization techniques.

Previous prior art models have one or more of the following limitations:(1) too long of a run time, (2) do not provide enough information, (3)are too simplistic, and/or (4) are not implemented in a format that canbe leveraged for automated explorations of possible design spaces.

The models of the present disclosure provide a balance of run time andmodel accuracy/complexity that has been achieved through selecting fastrunning analytical models and target key enhancements that areapplicable to plasma filtration from undiluted whole blood. Enablingautomated explorations was enabled through implementing the models inthe MATLAB scientific computing language using good practices of memorymanagement and code development for robustness and plug-and-playcapabilities.

The nature of the developed model is to make some large simplifyingassumptions that would enable this relationship to be included inanalytical fluid dynamic calculations that require a constant viscosity.The technique allows viscosity to vary with hematocrit but keepsviscosity constant under the different fluidic forces at work during theflow of blood in rectangular microchannels.

The assumptions that enable the mathematical derivation of theanalytical models include: constant fluid properties under fluidicforces of shear and pressure, no gravitational forces, full-developedflow, steady (constant/unchanging) flow conditions with respect to time,and that blood flow occurs in channels with a rectangular cross-section.

The hemolysis models are designed to capture the dependence of red bloodcell damage as a function of mechanical load and exposure time. The twomechanical loading mechanisms included in the suite of models are shearstress caused by general fluid flow and filtration forces caused bycells entrapped within the pores of the filtration membrane. Fluid shearstress is primarily considered at the nonmoving walls where the shearforces are at their maximum value.

A threshold value of shear stress and exposure time was used as onehemolysis criteria for human red blood cells. A second hemolysiscriterion was a model for the mechanical loading of red blood cellmembrane caused by cellular entrapment in the filtration pores. Thus,the two fluidic values that are assessed whether they are below thecalculated hemolysis thresholds are the wall shear stress and thepressure drop along the microchannel length.

The suite of models was also supported with empirical data that themechanical forces from filtration and filtration membrane pore clogginghave a higher hemolysis risk than shear induced hemolysis from bulkfluid shear forces.

The models of the present disclosure include a suite of analyticalmodels for a single pass cross-flow filtration. The models of thepresent disclosure provide an enhanced analytical modeling introductionhaving an intended use for the explorations of broad ranges ofoperational and design parameters, prioritizes speed over accuracy, andattempts to enhance accuracy with targeted model improvements that stillmaintain fast calculation times.

Referring to FIG. 9, a first flow chart of an exemplary considerationsof the present disclosure is illustrated.

Referring to FIG. 10, a cross-flow filtration concept of the presentdisclosure includes a track-etch membrane (TEM), the pressure drop alongthe channel above the TEM contributes to the transmembrane pressure thatdrives plasma through the TEM, and the flow across the TEM helps preventpore clogging and membrane fouling.

In one embodiment, inputs to the suite of analytical models andcalculations include (1) whole blood hematocrit prior to filtration, (2)dimensions of channel above TEM including height, width, and length, (3)duration (time) of filtration, and (4) flow conditions including bloodvolumetric flow rate across TEM, the pressure drop along channel aboveTEM, and the volume of blood to be transported over the TEM during thetime of filtration.

In one embodiment, outputs to the suite of analytical models andcalculations include (1) plasma flow rate through the TEM, (2) netplasma yield volume after the duration of filtration, and (3) hemolysispotential through fluid shear stress and red blood cell entrapmentwithin TEM pores including ensuring wall shear stress is below publishedcritical values (1500 dyne/cm²) and ensuring shear rate along TEM andmaximum transmembrane pressure keeps red blood cell membrane tensionbelow critical value.

Referring to FIGS. 11-13, additional flow charts of exemplaryembodiments of the present disclosure are illustrated.

The models of the present disclosure include the following calculationassumptions and limitations. The blood transport has a viscosity that isdependent on hematocrit only and the density is calculated using alinear rule of mixtures. The fluid dynamics calculations include thefollowing: (1) a channel that has a rectangular cross section, (2)steady-state conditions that are constant over time, (3) a constanthematocrit over all channel dimensions, (4) a flow rate across TEM thatis not decreased over a TEM length, and (5) a TEM width and length thatis equal to the channel width and length. The filtration model includes(1) a TEM that is already wetted, (2) steady-state conditions that areconstant over time, (3) a channel width only included in the flow rateacross TEM, (4) uses flow rate across TEM and not transmembranepressure, and (5) no cake layer formation is included in plasma flowrate or yield volume calculations. The hemolysis models include that thecontact time between the cells and TEM is linearly related to theinverse of the shear rate along the TEM and a pressure drop along thechannel above TEM is equal to the maximum transmembrane pressure.

The models of the present disclosure include the following recommendeduses: (1) reduce the selected operating parameters' risk of hemolysisdue to red blood shear stress and red blood cell entrapment, (2) balanceor tune system physics: flow rates in channel above membrane withreduced risk of hemolysis but generate sufficient volume of filteredplasma, pressure drop and flow rate in different sized channels, andmaximize plasma volume while ensuring minimal hemolysis, and (3)determine the amount of blood to flow over membrane to generatesufficient volume of filtered plasma.

While this disclosure has been described as having exemplary designs,the present disclosure can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A biological fluid separation device adapted toreceive a biological fluid sample having a first portion and a secondportion, the biological fluid separation device comprising: a housing,comprising: a first chamber having a first chamber inlet for receivingthe biological fluid sample therein and a first chamber outlet whereinthe first chamber outlet is placed a lateral distance from the firstchamber inlet in the first chamber; a second chamber having a secondchamber inlet and a second chamber outlet, and a separation memberseparating at least a portion of the first chamber outlet and the secondchamber, wherein the separation member defines a lateral flow path alongthe lateral distance from the first chamber inlet to the first chamberoutlet and is adapted to restrain the first portion of the biologicalfluid sample within the first chamber and to allow at least a portion ofthe second portion of the biological fluid sample to pass into thesecond chamber; an actuator; a first line in communication with theactuator and the first chamber; and a second line in communication withthe actuator and the second chamber, wherein the actuator is a vacuumsource that provides a first pressure at the first chamber outlet and asecond pressure at the second chamber outlet, wherein the first pressureis different from the second pressure and wherein, in response to theactuator the biological fluid sample is drawn into the first chamber viathe first line, and the second portion of the biological fluid sample isdrawn into the second chamber via the second line.
 2. The biologicalfluid separation device of claim 1, wherein a single actuator provides afirst pressure to a portion of the first chamber via the first line anda second pressure to a portion of the second chamber via the secondline.
 3. The biological fluid separation device of claim 1, wherein thebiological fluid sample is whole blood, the first portion is a red bloodcell portion and the second portion is a plasma portion.
 4. Thebiological fluid separation device of claim 1, wherein the vacuum sourceis an evacuated tube.
 5. The biological fluid separation device of claim1, wherein the second chamber is a plasma collection container.
 6. Thebiological fluid separation device of claim 1, further comprising aplasma collection container in communication with the second chamber. 7.The biological fluid separation device of claim 1, wherein theseparation member comprises a track-etched membrane.
 8. The biologicalfluid separation device of claim 1, further comprising a vent incommunication with a portion of the second chamber, the venttransitionable between a closed position in which the vent seals thesecond chamber, and an open position in which the second chamber isvented to atmosphere.
 9. The biological fluid separation device of claim8, wherein the vent is provided in the closed position during separationof the second portion of the biological fluid sample from the firstportion of the biological fluid sample, and in the open position duringremoval of the second portion of the biological fluid sample from thesecond chamber.
 10. The biological fluid separation device of claim 1,further comprising a porous material disposed within at least a portionof the second line.